How do you evaluate sin^-1(sin((19pi)/10))sin1(sin(19π10))?

1 Answer
Jul 26, 2017

-pi/10π10

Explanation:

sin^-1(x)sin1(x) is a number (or angle), tt in [-pi/2,pi/2][π2,π2]
with sin(t) = xsin(t)=x

So,

sin^-1(sin((19pi)/10))sin1(sin(19π10)) is a number (or angle), tt in [-pi/2,pi/2][π2,π2]
with sin(t) = sin((19pi)/10)sin(t)=sin(19π10)

(19pi)/1019π10 is almost 2pi2π, so it is a fourth quadrant angele.

The reference angle for (19pi)/1019π10 is pi/10π10.

So t = -pi/10t=π10